1. Field
This invention relates to the handling of saturated vapor streams. It is particularly directed to a condensate separator system for use in connection with chemical vapor sterilizers.
2. State of the Art
Chemical vapor sterilizers produce a quantity of used sterilant which cannot under modern constraints be directly discharged. Following a sterilizing procedure, used chemical sterilant is commonly condensed and collected in a reservoir for eventual safe disposal. The chemical vapor is typically passed through cooling coils to bring its temperature to below the vaporization temperature (e.g., 60.degree.-70.degree. C.) of its constituents. The remaining vapor stream may be discharged to the atmosphere. This stream may be discharged through the accumulated liquid sterilant prior to being vented to the atmosphere. Chemical sterilants often include water as a major constituent, and the vapor stream leaving the sterilizer may be saturated with respect to water. The vent stream following condensation is typically saturated, and includes condensed droplets of water and chemical sterilant. Current safety standards require that the vent stream pass through a chemical filter to reduce its chemical sterilant composition to trace amounts. Entrained moisture and condensate interfere with this process and shorten the useful life of a chemical filter. Entrained moisture and condensate can also cause a water hammer effect in the piping leading to the filter. It would be desirable to remove these constituents from the vent stream so that relatively dry vapor reaches the filter. Unfortunately, conventional steam traps and other well-known condensate collectors are either ineffective or unacceptably complex for this purpose.
Certain modern sterilizers may be operated optionally with steam or chemical sterilant cycles. Accordingly, the waste reservoir may at any given time contain a proportion of water ranging up to 100 percent. Similarly, the vent stream from a steam cycle may contain droplets of water only. It is not economically practical to provide separate venting systems for vent streams containing insignificant quantities of chemical sterilants. Accordingly, the chemical filters in such systems are exposed to entrained moisture following each sterilization cycle.
Steam trap devices of various types are used for removing condensate at saturated steam temperatures. These devices are not effective for use at temperatures close to ambient. The vent streams of a chemical sterilizer are typically much closer to ambient temperature (e.g. 60.degree. C.) than to saturated steam temperatures (e.g. 130.degree. C.).
U.S. Pat. No. 4,004,604 discloses a method and apparatus for drawing condensate from a steam-containing system. The apparatus is configured as a valve with a cascade section responsive to changes in the physical nature of medium in the section, thereby permitting liquid flow but blocking vapor flow.
U.S. Pat. No. 4,302,227 discloses a complex baffled moisture separator.
U.S. Pat. Nos. 4,447,394 and 4,764,351 describe sterilization methods utilizing formaldehyde, but lacking a condensate separator for the vent stream.
There remains a need for a low-cost, effective means for removing moisture and condensate from the vent stream of a chemical sterilizer at close to ambient temperature and pressure conditions.